Approximately what percentage of patients with Thyroid Eye Disease will also develop Myasthenia Gravis?

• A. 0.5%
• B. 5%
• C. 10%
• D. 1%

Answer: (D)

Autoimmune disorders can affect the eye in different ways, and they can occur together, but this overlap is relatively uncommon. In patients who have Thyroid Eye Disease, the chance of also having Myasthenia Gravis is about one in a hundred. That small amount reflects the fact that while the two conditions share an autoimmune basis, their simultaneous appearance is not a common finding. Higher percentages like 5% or 10% would imply a much stronger linkage than is typically seen, and while estimates can vary a bit between studies, roughly 1% is the best single approximation. If a TED patient shows fatigable lid weakness or diplopia that fluctuates with activity, MG should be considered and evaluated appropriately.